Multifunctional Peroxidase-Mimicking Ag₂S/NiS/Reduced Graphene Oxide Nanozyme for Hydrogen Peroxide Determination and...

Hydrogen peroxide (H₂O₂) is an environmentally beneficial intermediate essential to human biological metabolism. However, the human body may suffer serious cellular damage because of the overproduction and buildup of excess H₂O₂. For the detection of H₂O₂, the Ag₂S/NiS-adhered reduced graphene oxide (Ag₂S/NiS/rGO) nanozyme was developed, which oxidizes 3, 3, 5, 5-tetramethylbenzidine (TMB) into a blue-colored product, resulting in the development of an efficient and cost-effective colorimetric method. In real sample analysis, this approach showed good recovery (97.5%-100.6%) and a sensitivity to H₂O₂ concentrations from 0.1 to 100 mM, with the lowest limit of H₂O₂ observed at 0.1 mM, with K_m value as low as 0.498 mM. Additionally, investigations on selectivity, storage stability (3 weeks), and recycling stability were conducted. The same nanozyme is also utilized to remove organic dyes when H₂O₂ is present. According to the results, methyl orange (MO) and rhodamine B (RhB) dyes decay in 8 and 6 min, respectively, with apparent rate constants of 0.02287/min for MO and 0.02132/min for RhB. This multifunctional nanozyme offers a promising platform for real-time environmental monitoring and sustainable wastewater treatment by enabling sensitive H₂O₂ detection and rapid degradation of hazardous organic dyes.